JPS63106961A - System for preventing breakdown of recording format - Google Patents

Abstract

PURPOSE:To prevent a recording format from being broken down, by invalidating a write signal from a host device at parts where sector identifying information which identifies each sector is recorded. CONSTITUTION:The write signal from the host device is invalidated between the parts where the sector identifying information which identifies each sector is recorded. In other words, the number of bytes equivalent to the completing position of an ID part in one sector is set in advance by a switch circuit 1, and the value is loaded initially to a counter 2 responding to an index pulse or a sector pulse. Simultaneously, a count enable F/F3 and a write prohibition F/F4 are set, and the counter 2 counts down at every inputting of a byte clock, and when the content arrives at a prescribed initial value decided by the switch circuit 1, both F/Fs 3 and 4 are reset responding to the above state until the next index pulse or sector pulse arrives. In such a way, it is possible to prevent the recording format from being broken down due to the malfunction of the host device, etc., in advance.

Description

TECHNICAL FIELD The present invention relates to a recording format destruction prevention method, and more particularly to a recording format destruction prevention method in a fixed sector type magnetic disk device.

PRIOR ART Conventionally, there has been a format destruction prevention measure known as write protection for magnetic disks, but this preventive measure is simply a method of prohibiting writing and making it read-only, and when it is necessary to write or read data. It is unsuitable for In other words, the conventional format destruction prevention method simply prohibits writing by hardware.
The disadvantage is that the magnetic disk device becomes read-only.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a recording format destruction prevention method for a magnetic disk device that makes it possible to prevent format destruction while maintaining data writing and reading capability.

Structure of the Invention According to the present invention, there is provided a recording format destruction prevention method in a fixed sector type magnetic disk device, in which writing from a host device is prevented at least during a portion in which sector identification information for identifying each sector is recorded. A recording format destruction prevention method characterized by invalidating the signal is obtained.

Example Embodiments of the present invention will be described in detail below with reference to the drawings.

First, referring to FIG. 2, a fixed sector format and a corresponding write inhibit signal waveform are shown.

In the fixed sector format, as shown in the figure, all 10 copies in each sector O to N (N is a positive integer) are physically fixed and recorded. This ID part is identification information of the sector in which it is included. Since the position of each ID section does not change, the 10 sections can be identified by counting the clock signals for the servo board that the device creates from the servo surface (not shown). Therefore, it is easy to obtain a write inhibit signal as shown in FIG. 2, which forcibly inhibits writing only to at least this ID section.

Therefore, an embodiment block of the present invention as shown in FIG. 1 is obtained. Since the number of bytes at the end position of the ID part in one sector is fixed and known in advance in the fixed sector method as described above, byte number information corresponding to this number of bytes is initially set in the down counter 2 by the switch 1. . This initial setting of the counter 2 is performed in synchronization with the generation timing of the index pulse or sector pulse recorded at the beginning of each sector shown in FIG. Therefore, an OR gate 6 is provided, and the index pulse and the sector pulse are supplied to the load terminal of the counter 2 via this OR gate 6.

A byte clock is used as a down count pulse for this counter 2, and this byte clock is input to the count down of the counter via an AND gate 7. The output of this counter 2 becomes a reset input of a count enable F/F (flip-flop) 3, and the output of an OR gate 6 is used as the set input. The Q output of the F/F 3 is used as the gate signal of the AND gate 7 which inputs the byte clock.

The output of the counter 2 serves as a reset input for the write-protected F/F 4, and the output of the OR gate 6 is supplied to its set input. The Q output of this F/F 4 is supplied to an input/output control circuit (not shown) via a Nant gate 8 and an AND gate 9.

The output of the switch circuit 5 is applied to other inputs of the Nandt gate 8, and a write gate signal from a host device (not shown) is applied to other inputs of the AND gate 9.

In this configuration, the number of bytes corresponding to the end position of the ID portion in one sector is set in advance by the switch circuit 1, and this value is initially loaded into the down counter 2 in response to an index pulse or a sector pulse. At the same time, count enable F/F3 and entry/exit prohibition F/
F4 is set. Therefore, the counter 2 counts down each time the byte clock is input, and when the contents reach the initial value determined by the switch circuit 1, the counter 2 counts down until the next index pulse or sector pulse arrives in response. Reset both F/Fs 3 and 4. Therefore, the output of write-protected F/F4 is as shown in Figure 2.
It can be seen that the write inhibit signal includes the ID part.

The switch circuit 5 and the Nant gate 8 are used to select whether or not this write inhibit signal is valid.

It is clear that the circuit example shown in FIG. 1 is merely an example, and that various modifications are possible.

Effects of the Invention As described above, according to the present invention, at least I in the sector
By adding a circuit that protects the D section from writing, it becomes possible to prevent format destruction caused by malfunction of the host device, and also makes it read-only due to the measures taken to prevent such destruction. It has the effect of being able to solve problems.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram of an embodiment of the present invention, and FIG. 2 is a diagram correspondingly showing the fixed sector format and write inhibit signal timing used in the present invention. Explanation of symbols of main parts 1...Initial setting switch 2...Down counter

Claims (1)

[Claims] A recording format destruction prevention method in a fixed sector type magnetic disk device, characterized in that a write signal from a host device is invalidated at least during a portion in which sector identification information for identifying each sector is recorded. Recording format destruction prevention method.